Multilayer solid golf ball

ABSTRACT

The present invention provides a multilayer solid golf ball having an enclosing layer between a core and a cover. The core has a coefficient of restitution (COR) greater than 0.750, and the enclosing layer has a thermal conductivity less than or equal to 0.20 W/m-K. The enclosing layer with low thermal conductivity may reduce the decrease of the COR of the ball in a cold weather that improves the ball control and the flying distance.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a golf ball and, more particularly, toa multilayer solid golf ball having an enclosing layer with a lowthermal conductivity therein.

2. Description of the Related Art

The flying distance is an important index that we evaluate a golf ball.There are three main elements affecting the flying distance of the golfball and they are “initial velocity”, “spin rate”, and “launch angle”.Initial velocity is one of the primary physical properties affecting theflying distance of the golf ball. The coefficient of restitution (COR)is an alternate parameter of initial velocity of the golf ball, and thetemperature will affect the COR. Taking 24° C. as the standardtemperature, the physical properties, including the COR, of the golfball will be affected when the temperature is lower than 24° C. We findthat the COR is significantly positive relative to the temperature, sothe golf ball usually flies shorter in a cold weather.

When playing golf in a cold weather, 0° C. for example, a golfer maytake one or more ways to warm the ball, including using body temperatureor a golf ball heater, to raise the temperature of the golf ball so asto raise the COR of the golf ball that the golfer may drive the ballfurther. However, above warming ways cannot keep the raised temperatureof the golf ball for a long time. Therefore, the raised COR of the golfball cannot be kept for a long time by using above-mentioned ways. Thetemperature will drop quickly when the ball leaves the golfer's body orthe golf ball heater, which will deteriorate the COR of the ball too.The sudden changes of the COR make it difficult for the golfer topredict and control the flying distance of the ball. Therefore, there isstill a need to reduce the affection of the low temperature to the CORof the golf ball.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide amultilayer solid golf ball, which has better properties in flyingdistance and ball control in a cold weather.

To achieve the objective of the present invention, a multilayer solidgolf ball includes a core having a COR greater than 0.750, a coversurrounding the core, and an enclosing layer between the core and thecover. The enclosing layer has the thermal conductivity less than orequal to 0.20 W/m-K.

The present invention provides the enclosing layer with the low thermalconductivity between the core and the cover to improve the CORdeterioration of the ball in a cold weather that may help the ballcontrol and the flying distance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a first preferred embodiment of thepresent invention; and

FIG. 2 is a sectional view of a second preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, a multilayer solid golf ball 100 of the firstpreferred embodiment of the present invention includes a core 10, acover 20, an intermediate layer 30, and an enclosing layer 40.

The core 10 has the COR greater than 0.750, more preferably greater than0.770, and most preferably greater than 0.790. The core 10 may be madefrom a thermoplastic material or a thermosetting material, and thethermoplastic material is preferred. The thermoplastic material of thecore 10 may be selected from the group consisting of ionomer resin,polyamide resin, polyester resin, polyurethane resin, and a mixturethereof. In the present embodiment, ionomer resin is preferred for thecore 10. The suitable ionomer resin includes HPF and Surlyn®, bothcommercially available from E. I. Dupont de Nemous and Company, andIOTEK®, commercially available from Exxon Corporation. To get thegreater COR, a main composition of the core 10 is preferably HPF, andSurlyn® and/or IOTEK® are sub-compositions which are optionally addedtherein. The sub-composition of the core 10 is in an amount of 0 to 10parts by weight, based on 100 parts by weight of the main composition ofthe core 10. The core 10 may be made by hot-press molding or injectionmolding, and injection molding is preferred. The core 10 of the presentinvention may be single layer or multilayer construction, and except forthe aforementioned materials, any other materials may be also used tomake the core 10, as long as the core 10 has the COR greater than 0.750.A diameter of the core 10 may be in a range between 19.0 mm and 37.0 mm,a preferred diameter range is between 21.0 mm and 35.0 mm, and a morepreferred diameter range is between 23.0 mm and 32.0 mm. The core 10 hasan outer surface 11.

There is no specific limitation for the material of the cover 20. Anyconventional material that is used to make the cover 20 may be used inthe present invention.

The intermediate layer 30 has an inner surface 31 facing the enclosinglayer 40 and an outer surface 32 facing the cover 20. The intermediatelayer 30 may be made from a thermoplastic material or a thermosettingmaterial. In the present invention, the thermosetting material ispreferred, such as rubber composition. There are some base rubber thatmay be used in the rubber composition, such as 1,4-cis-polybutadiene,polyisoprene, styrene-butadiene copolymers, natural rubber, and amixture thereof. To have a better resilient performance,1,4-cis-polybutadiene is preferred. Alternatively, 1,4-cis-polybutadienecan be used as the base material for the intermediate layer 30 and mixedwith other ingredients. However, the amount of 1,4-cis-polybutadieneshould be at least 50 parts by weight, based on 100 parts by weight ofthe rubber composition.

Except for the base rubber of 1,4-cis-polybutadiene, other additives,such as a crosslinking agent and a filler with a greater specificgravity may be added to the rubber composition. The suitablecrosslinking agent can be selected from the group consisting of zincacrylate, magnesium acrylate, zinc methacrylate, and magnesiummethacrylate. To get greater resilience, zinc acrylate is preferred. Toincrease a specific gravity, a suitable filler may be added in therubber composition, such as zinc oxide, barium sulfate, calciumcarbonate, and magnesium carbonate, and in the present invention, zincoxide is preferred. In addition, a metal powder with a greater specificgravity may also be used as the filler, such as tungsten. By means ofadjusting the added amount of the filler, the specific gravity of theintermediate layer 30 can reach the desired level. The thickness of theintermediate layer 30 is in a range between 2.0 mm and 11.0 mm, morepreferably in a range of 2.1 mm and 9.5 mm, and most preferably in arange between 3.6 mm and 8.5 mm.

The enclosing layer 40 is between the core 10 and the intermediate layer30. To keep the COR of the multilayer solid golf ball 100, the thicknessof the intermediate layer 30 is less than or equal to 1 mm, morepreferably in a range between 0.005 mm and 0.70 mm, and most preferablyin a range between 0.01 mm and 0.4 mm. If the thickness of the enclosinglayer 40 is less than 0.005 mm, the low thermal conductivity effect ofthe intermediate layer 40 is not significant. In the present embodiment,the enclosing layer 40 directly covers the outer surface 11 of the core10. In other words, the enclosing layer 40 has an inner surface 41contacting the outer surface 11 of the core 10 and an outer surface 42contacting the inner surface 31 of the intermediate layer 30. Theenclosing layer 40 is made from a material with a lower thermalconductivity. The thermal conductivity of the enclosing layer 40 islower than that of the cover 20 or that of the intermediate layer 30. Inthe present embodiment, a value of the thermal conductivity of theenclosing layer 40 is less than or equal to 0.20 W/m-K so that theenclosing layer 40 will have a superior performance in reducing theconductivity of the cold from the cover 20 to the core 10. The thermalconductivity of the enclosing layer 40 is preferred between 0.04 W/m-Kand 0.15 W/m-K, and is more preferred between 0.06 W/m-K and 0.15 W/m-K.In the present embodiment, the material of the enclosing layer 40 can beselected from the group consisting of ethylene vinyl acetate,polyurethane, polyester, polyamide, polyisoprene, polyvinyl chloride,acrylonitrile butadiene styrene, polyvinylidene fluoride, polyimide, anda mixture thereof. The material of the enclosing layer 40 is not limitedto the above materials, any material having a thermal conductivitywithin the limitation of the present invention may be used.

As shown in table 1 to table 5, please compare with the Examples 1 and 3and the Comparative Examples 1 and 3. The COR of the multilayer solidgolf ball 100 of the present invention with the enclosing layer 40 willdrop slower in a cold environment than the conventional multilayer golfball without the enclosing layer, which proves that the multilayer solidgolf ball 100 of the present invention has the higher COR in a coldenvironment to get a further flying distance and a better ball control.

There are still many ways to provide the enclosing layer 40. FIG. 2shows a multilayer solid golf ball 200 of the second preferredembodiment of the present invention, in which an alternate enclosinglayer 80 is provided. The multilayer solid golf ball 200, as same as themultilayer solid golf ball 100 of the first preferred embodiment,includes a core 50, a cover 60, an intermediate layer 70, and theenclosing layer 80. The different part is that the enclosing layer 80 isprovided between the intermediate layer 70 and the cover 60. Theenclosing layer 80 has an inner surface 82 contacting an outer surface71 of the intermediate layer 70 and an outer surface 81 contacting aninner surface 61 of the cover 60. The performance of the multilayersolid golf ball 200 of the second preferred embodiment is shown in table5 also. Please compare with the Examples 2 and 4 and the ComparativeExamples 2 and 4, the COR of the multilayer solid golf ball 200 of thepresent invention with the enclosing layer 80 will drop slower in a coldenvironment than the conventional multilayer solid golf ball without theenclosing layer, which proves that the multilayer solid golf ball 200 ofthe present invention has the higher COR in a cold environment to get afurther flying distance and a better ball control.

The location of the enclosing layer is not limited in above preferredembodiments. As long as the enclosing layer is provided between the coreand the cover, it may achieve the objective of the present invention.

In conclusion, the present invention provides a multilayer solid golfball having an enclosing layer with lower thermal conductivity betweenthe core and the cover of the multilayer solid golf ball that may reducethe conductivity of the cold from the cover to the core to make the golfball still keep a sufficient COR in a cold environment.

Although a particular embodiment of the invention has been described indetail for purposes of illustration, various modifications andenhancements may be made without departing from the spirit and scope ofthe invention. Accordingly, the invention is not to be limited except asby the appended claims.

TABLE 1 Core Resin Blend A HPF 2000* 100 *HPF 2000 is trade name ofionomeric resin by E. I. DuPont de Nemours and Company

TABLE 2 Intermediate layer Rubber compound B C TAIPOL BR0150* 100 100Zinc acrylate 28 26 Zinc oxide 6 4.5 Barium sulfate 39.5 32 Peroxide 1 1*TAIPOL BR0150 is the trade name of rubber by Taiwan Synthetic RubberCorp.

TABLE 3 Enclosing layer D E Methyl ethyl ketone 31 33 Methyl cyclohexane57 58 ethylene vinyl acetate 12 9

TABLE 4 Cover Resin blend F Surlyn ® 8940* 50 Surlyn ® 9910* 50*Surlyn ® 8940 and Surlyn ® 9910 are trade names of ionomeric resin byE. I. DuPont de Nemours and Company

TABLE 5 Example Comparative Example 1 2 3 4 1 2 3 4 Core Blend A A A A AA A A Diameter (mm) 24 24 28 28 24 24 28 28 Weight (g) 7.0 7.0 11.1 11.17.0 7.0 11.1 11.1 Specific gravity 0.96 0.96 0.96 0.96 0.96 0.96 0.960.96 Surface Shore D hardness 53 53 53 53 53 53 53 53 Compression,10-130 kg 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.6 (mm) Core COR* 0.8471 0.84740.8459 0.8461 0.8472 0.8474 0.8460 0.8459 Intermediate layer Compound CC B B C C B B Diameter (mm)** 39.3 39.3 39.3 39.3 39.3 39.3 39.3 39.3Weight (g)** 36.8 36.8 36.8 36.8 36.8 36.8 36.8 36.8 Specific gravity**1.17 1.17 1.17 1.17 1.17 1.17 1.17 1.17 Surface Shore D hardness 41 4143 43 41 41 43 43 Compression, 10-130 kg 3.3 3.3 3.2 3.2 3.3 3.3 3.2 3.2(mm)** Enclosing layer Blend E E D D None None None None Thickness (mm)0.02 0.02 0.02 0.02 — — — — Thermal conductivity 0.12 0.12 0.10 0.10 — —— — (W/m-K)*** Enclosing core Yes — Yes — — — — — Enclosing intermediate— Yes — Yes — — — — layer Cover Blend F F F F F F F F Thickness 1.711.71 1.71 1.71 1.7 1.7 1.74 1.74 Specific gravity 0.99 0.99 0.99 0.990.99 0.99 0.99 0.99 Surface Shore D hardness 69 69 69 69 69 69 69 69Ball Weight (g) 45.4 45.4 45.4 45.4 45.4 45.4 45.4 45.4 Diameter (mm)42.7 42.7 42.7 42.7 42.7 42.7 42.7 42.7 Compression, 10-130 kg 2.8 2.82.9 2.9 2.8 2.8 2.9 2.9 (mm) Ball COR* 24° C. 0.8101 0.8105 0.81230.8124 0.8112 0.8110 0.8128 0.8132  0° C. × 10 mins 0.7828 0.7825 0.78710.7830 0.7751 0.7781 0.7795 0.7804  0° C. × 20 mins 0.7717 0.7713 0.77890.7748 0.7648 0.7683 0.7712 0.7720  0° C. × 30 mins 0.7663 0.7660 0.77360.7685 0.7601 0.7635 0.7667 0.7670 *For the COR test of the presentinvention, the initial velocity is 40 m/sec. **Value of core +intermediate layer + enclosing layer. ***Thermal conductivity ismeasured by a thermal conductivity analyzer, Hot Disk TPS 2500 with thinfilm module, commercially available from Hot Disk AB company, Sweden.

1. A multilayer solid golf ball comprising: a core having a coefficientof restitution greater than 0.750; a cover surrounding said core; and anenclosing layer, which is provided between said core and said cover,having a thermal conductivity less than or equal to 0.20 W/m-K.
 2. Themultilayer solid golf ball as claimed in claim 1, further comprising anintermediate layer, which is provided between said enclosing layer andsaid cover, having an inner surface facing said enclosing layer, whereinsaid enclosing layer has an outer surface contacting said inner surfaceof said intermediate layer.
 3. The multilayer solid golf ball as claimedin claim 2, wherein said enclosing layer has an inner surface, and saidcore has an outer surface contacting said inner surface of saidenclosing layer.
 4. The multilayer solid golf ball as claimed in claim1, further comprising an intermediate layer, which is provided betweensaid enclosing layer and said core, having an outer surface facing saidenclosing layer, wherein said enclosing layer has an inner surfacecontacting said outer surface of said intermediate layer.
 5. Themultilayer solid golf ball as claimed in claim 4, wherein said cover hasan inner surface, and said enclosing layer has an outer surfacecontacting said inner surface of said cover.
 6. The multilayer solidgolf ball as claimed in claim 1, wherein said cover has a thermalconductivity greater than said thermal conductivity of said enclosinglayer.
 7. The multilayer solid golf ball as claimed in claim 4, whereinsaid cover has a thermal conductivity greater than said thermalconductivity of said enclosing layer.
 8. The multilayer solid golf ballas claimed in claim 2, wherein said intermediate layer has a thermalconductivity greater than said thermal conductivity of said enclosinglayer.
 9. The multilayer solid golf ball as claimed in claim 1, whereinsaid thermal conductivity of said enclosing layer is in a range between0.04 W/m-K and 0.15 W/m-K.
 10. The multilayer solid golf ball as claimedin claim 1, wherein said thermal conductivity of said enclosing layer isin a range between 0.06 W/m-K and 0.15 W/m-K.
 11. The multilayer solidgolf ball as claimed in claim 1, wherein said enclosing layer is madefrom a material selected from the group consisting of ethylene vinylacetate, polyurethane, polyester, polyamide, polyisoprene, polyvinylchloride, acrylonitrile butadiene styrene, polyvinylidene fluoride,polyimide, and a mixture thereof.
 12. The multilayer solid golf ball asclaimed in claim 1, wherein said enclosing layer has a thickness lessthan or equal to 1 mm.
 13. The multilayer solid golf ball as claimed inclaim 1, wherein said enclosing layer has a thickness between 0.005 mmand 0.70 mm.
 14. The multilayer solid golf ball as claimed in claim 1,wherein said enclosing layer has a thickness between 0.005 mm and 0.40mm.
 15. The multilayer solid golf ball as claimed in claim 1, whereinsaid coefficient of restitution of said core is greater than 0.770. 16.The multilayer solid golf ball as claimed in claim 1, wherein saidcoefficient of restitution of said core is greater than 0.790.
 17. Themultilayer solid golf ball as claimed in claim 1, wherein said core ismade from a thermoplastic material.
 18. The multilayer solid golf ballas claimed in claim 17, wherein said thermoplastic material is made froma material selected from the group consisting of ionomer resin,polyamide resin, polyester resin, polyurethane resin, and a mixturethereof.
 19. The multilayer solid golf ball as claimed in claim 1,wherein said core has a diameter between 19.0 mm and 37.0 mm.
 20. Themultilayer solid golf ball as claimed in claim 1, wherein said core hasa diameter between 21.0 mm and 35.0 mm.
 21. The multilayer solid golfball as claimed in claim 1, wherein said core has a diameter between23.0 mm and 32.0 mm.